Design And Implementation Of SD Storage Card

SD Card is one of the most popular storage media in the world, as is largely applied in Mobile Phone, Digital Still Camera, MP3 Player, Digital Video Camera, and so on. 30% of total quantities are in the application of Mobile Phone. SD Card is not only the highest share, but also the most fast in the storage card market. Except high speed, low cost, big capacity and small size, high security is also outstanding of SD card. But popular SD Card's reading speed is only 7MB/s, and one's writting speed is 2MB/s.The paper gives an implementation instance base on the design discussion. The implementation focuses on speed enhancement. Though System Architecture, Development Environment, Base Module Design, and Read/Write Module Design, it can achieve the speed of 20MB/s and 12MB/s.Though using controller and Nand Flash, Paper implements SD's hardware. Controller of them is the focus of our research. The system implements low cost, achieves high speed and reaches high security feature through using four modules. The controller includes the following four modules: SD Communication Module, Nand Flash Storage Control Module, CPRM Security Control Module, and Micro Controller Module (8051). After researching deeply of their requirement and characteristics, author goes to analysis and design in project.To provide the real-time Communication of SD, system implements MAC layer through hardware design. So it achieves real time. In the chapter 3 discuss the SD interface design. From physical layer protocol, MAC layer protocol, to application layer protocol it discusses SD communication module.Physical layer focuses on pin definition and other issues. MAC layer's discussion includes frame construction, error control and flow control. Application layer focuses on command parser and response generation. And command divides into the following three categories: The command of State Machine Control, the one of SD Register Read and write, and the one of Data read and write.Nand Flash is the data center of the whole system. Data Integrity and Security is the key of the system. Nand Flash Storage Module's discussion is how to satisfy function requirement field. Function requirement includes operating mapping and address mapping. Address mapping is mapping logical address to physical address. Operating mapping is mapping the operation of sector's reading and writing to the operation of page's read and write and block's erase.